#include <iostream>
#include <cstdio>
using namespace std;
int nums[100];
int main(int argc, char** argv) {
int T;
scanf("%d", &T);
while (T--) {
int N;
scanf("%d", &N);
scanf("%d", &nums[0]);
if (N == 1) {
printf("1\n");
continue;
}
scanf("%d", &nums[1]);
int gap = nums[1] - nums[0];
int last = nums[1];
int maxLen = 2, len = 2;
for (int i = 2; i < N; ++i) {
int now;
scanf("%d", &now);
nums[i] = now;
if (now - last == gap) ++len;
else {
if (len > maxLen) maxLen = len;
gap = now - last;
len = 2;
}
last = now;
}
if (len > maxLen) maxLen = len;
printf("%d\n", maxLen);
}
return 0;
}
